This text is part of the special Environment section
How to reinvent agriculture to reduce its ecological footprint and ensure food security for a growing world population? A small part of the solution may well be at the root-soil interface, in the plant ‘microbiome’. It is on this aspect that INRS researchers are counting in order to improve the selection process and the competitiveness of cultivated plants.
In the near future, it is likely that our crops will have to deal with more droughts, floods or changes in soil composition. How will our grains and vegetables respond to stress and continue to be supplied with nutrients to grow to their maximum potential?
To improve plant varieties so that they can face these challenges, a team of researchers is focusing on selecting the most efficient plants in the absorption of nutrients. Under the effect of stress, how quickly are these nutrients taken up, distributed and stored by the plant? To precisely scan these mechanisms at the molecular level, the researchers use an innovative technology: the synchrotron type laser.
“We had problems imaging plants. The important thing was to make a three-dimensional X-ray over very short times, to see the relationship between the root system and the macroscopic development of the plant, or even to see how the plant evolves when we change the composition of the earth, for example,” explains Jean-Claude Kieffer, physicist at the National Institute for Scientific Research (INRS). He co-leads the project with Brian Ham of the Global Institute for Food Security (GIFS) in Saskatchewan. Project researchers focus on the interface between roots and soil, the rhizosphere, also considered the microbiome of plants.
In Canada, a machine makes it possible to make such images: the synchrotron, a huge particle accelerator located in Saskatoon. After having worked in the medical field, Jean-Claude Kieffer has been working for several years on a titanic task: developing a miniaturized version (about 10 square meters!) of synchrotron radiation that can be transported to the farm.
“We have set up a machine that operates very stable, with a rate of 2.5 images per second, rejoices the laser specialist, who lists many technical challenges to achieve such a result. It looks like holography with x-rays.”
“The idea is to make a rapid selection of plants and increase the volume of production in the Canadian plains,” continues the researcher. It is a unique program in the world! I have already been invited to present it in Russia. India was also extremely interested. With this technology, Mr. Kieffer hopes to contribute to solutions to ensure food security in the world. “I do a lot of fundamental physics, but it has to be useful! exclaims the enthusiast.
MicroRNAs to improve competitiveness
If the spreading of fertilizers ensures better food production, the activity generates environmental impacts such as the contamination of waterways. To reduce the amount of fertilizer prescribed for various crops, INRS PhD candidate in biology Jessica Dozois is trying to dissect some poorly understood mechanisms of the plant microbiome. Like our gut microbiome, it plays a role in nutrient absorption and could help reduce fertilizer requirements in the field.
“There are a lot of bacteria and microorganisms that are at the root level of plants,” she notes. Some of them allow the plant to better assimilate elements such as nitrogen, while others will compete with the plant for the same resources.
The researcher is looking into a mechanism that is still poorly understood in the relationship between the plant and different bacteria. Plants can secrete molecules to better defend themselves or be more competitive. By carefully sampling this thin layer between the soil and the roots, she discovered micro-RNAs, tiny single-stranded genetic fragments, which she managed to identify thanks to genetic sequencing.
It seems that by going to stick to the genetic code of the bacteria, these micro-RNAs can modify or even prevent the production of certain proteins having a role in the absorption of nutrients by the bacteria. These small molecules could therefore act as inhibitors blocking the assimilation of certain nutrients by bacteria, allowing more to be left for the plant. By stimulating the production of certain micro-RNAs, could the plant be satisfied with a reduced quantity of fertiliser? This is what Jessica Dozois hopes, who, after a master’s degree on this subject, is continuing her investigations on the question as part of a doctorate under the supervision of Étienne Yergeau.
These micro-RNAs have been synthesized, explains the doctoral student. “What we’re doing is putting them in the presence of an important bacterium to see what’s going on with different forms of nitrogen,” she says. Subsequently, Jessica Dozois hopes that small harmless molecules could be applied to plants to stimulate the production of very specific micro-RNAs, allowing them to be more competitive against certain bacteria.